.PS
.vs 10
[	A:	ellipse "$D sub 1$"
		arrow down .5 from last ellipse.s
	B:	ellipse fill light "$D sub 2$"
	T:	box fill light "$T sub 1$" "foo" with .w at B.e + .2,0
		arrow from B.e to T.w
		arrow dotted from A.e to T.n
	C:	ellipse fill dark "$D sub 3$" with .w at T.e + .2,0
	T2:	box fill dark "$T sub 2$" "foo" with .w at C.e + .2,0
		arrow from C.e to T2.w
		arrow dotted from A.e to T2.nw
		arrow from A.s to C.nw
	T3:	box fill light "$T sub 3$" "foo" with .n at T.s - 0,.4
		arrow dotted from T.s to T3.n
		arrow dotted from T2.s to T3.ne
		arrow from B.se to T3.nw
] 
.vs
.PE
